Press Alt+F9 to toggle from field codes to field results.
Sorry, I was too fast on the trigger. Suzanne's response is the
correct one.
There are two separate "Field codes" option boxes, one in the View tab
of the Tools > Options dialog and one on the Print tab. The Alt+F9
shortcut changes the setting of the one on the View tab only. If
you're seeing field codes in printed pages (and in Print Preview) but
not on the editing screen, the one on the Print tab is the culprit.
There isn't a keyboard shortcut for that.
It's still true, though, that both of your posts are about the same
setting.